Users listen to radio broadcasts in a number of settings, including from within their vehicles. The content of these broadcasts may include a variety of news, traffic, information, and/or music. In the past, a user's reception of radio broadcasts was limited by the geographical area of where the user was located. For example, when a user passed between geographical regions, the radio signals often became attenuated to the point that the radio broadcast lost clarity or was lost altogether.
In recent years, satellite radio has emerged as a new broadcasting source. Satellite radio broadcasts are transmitted using satellites that orbit the earth instead of the land based antennas associated with conventional broadcasting means. These transmissions are broadcast in a digital format, which enhances the quality of the broadcast received by radio users. The use of a satellite reduces and often eliminates the geographical limitations common to conventional radio broadcasts and allows for transmission of radio broadcasts across broad geographical regions, such as across the entire continental United States.
In addition to the elimination of geographical restrictions, satellite broadcasting typically includes a broad array of programs or listening selections. However, while providing a broad choice of listening selections, the broadcast of a signal across a broad geographical region complicates the reception and processing of locally relevant information such as traffic incidents or other geographically relevant information.
Currently, geographically relevant information concerning traffic is frequently transmitted using conventional radio broadcasts over an existing system. The data messages are delivered via public broadcast using the VHF and FM frequency bands that are known as the Radio Data System Traffic Management Channel (RDS-TMC). Recent efforts have been directed to implementing a similar system for a satellite radio system. However, these efforts are limited by the complexity of providing useful information to users at a given location via a signal transmitted across a broad geographical area.